Vapor Intrusion Diagram: USEPA
Vapor intrusion, or Vapour intrusion (VI) if you prefer, is one of the “hot topics” in the environmental world. While I was attending RemTec in Denver this past March, it was one of the tracks of discussion and dominated many of the conversations.
So what exactly is VI and why should you care? I asked one of our VI experts, Dr. Khaled Chekiri, to provide some insight on VI.
What is VI, and what is the “scientific concern”?
Dr. Chekiri: Vapor intrusion (VI) is the phenomenon by which volatile chemicals in soil or groundwater migrate from the subsurface into the air space of a building. Understanding VI is important because of the potential impact on our health and safety. Health concerns are considerable, because toxic chemicals often enter the bloodstream more easily through inhalation than other exposure pathways, like ingestion or dermal contact.
What are the questions or concerns surrounding VI?
Dr. Chekiri: There are several, the main one being the confusion surrounding it. The United States Environmental Protection Agency released the Draft VI rules in November 2002 (Draft OSWER Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soil). Since the November 2002 release, there has been wide disparity between various regulatory bodies (state and federal) and their approach to quantify VI. For example, requirements and procedures to investigate VI (including sampling protocols), assessment of results, and how to mitigate VI are often inconsistent and ambiguous. Further, many in the regulated community feel that they have been kept in the relative dark regarding what they should or shouldn’t do to assess VI risks on properties they may be purchasing.
What are the new developments?
Dr. Chekiri: In April 2013, USEPA prepared external review draft documents of two guidance documents regarding vapor intrusion:
1) A general guidance document for all compounds: “OSWER Final Guidance For Assessing And Mitigating The Vapor Intrusion Pathway From Subsurface Sources To Indoor Air – External Review Draft” and
2) A guidance document focused on petroleum hydrocarbons released from underground storage tanks: “Guidance For Addressing Petroleum Vapor Intrusion At Leaking Underground Storage Tank Sites – External Review Draft.”
The idea is that these guidance documents will help to provide some consistency for investigative, as well as mitigation, methods as it relates to VI. Whether they provide scientifically and technically sound approaches is yet to be determined. And if you want to weigh in on this question, the deadline for public comment is June 24, 2013.
Is there anything new in Michigan as it relates to VI?
Dr. Chekiri: In Michigan, the “Part 201/213 Vapor Intrusion Policy and Procedure” (the Policy) was revised and updated to include comments provided by stakeholders during the May 1 to August 1, 2012, comment period. The Policy is currently under review by senior management at the Michigan Department of Environmental Quality (DEQ) and is expected to be completed soon. Keep your eyes peeled! A notice will be sent out on the DEQ listserv notifying interested parties of the newly-finalized document.
What should I do in the interim?
Dr. Chekiri: First, if you are requested to test for vapor intrusion, we would continue to caution you to very carefully consider your options before moving forward with any sampling. The science of VI is still relatively young. However, legal issues surrounding environmental data are more mature, and once you have analytical results, you may have certain obligations that are best discussed with legal counsel. There are (in my opinion) better approaches to assess the potential impact of vapors than just sampling.
Second, keep a watchful eye on the regulatory developments, especially if you are buying or selling properties that may be impacted by VI. Real or perceived impact from VI could affect transactions and obligate a new owner to response actions under due care or continuing obligation rules.
And, of course, please call us at (248) 932-0228 or (519) 979-7300 with any questions you may have about VI or if you would like to discuss a peer review on a current investigation.